Such models as mock-ups or full-sized models of cars or household electronic products and master models or master mold forms are built of rigid foamed polyurethane blocks by cutting. Rigid foamed polyurethane blocks as modeling stock are made by such processes as one in which a basic material composition is mixed with hollow microspheres as weight-reducing agent and is allowed to cure in a mold and another one in which an inert gas is dispersed in the basic material composition by an agitator to reduce weight and the composition is allowed to cure in a mold in that state. The latter is known as a mechanical frothing method. Those techniques are disclosed in U.S. Pat. Nos. 4,916,173 and 5,401,785.
The problem with the prior art rigid foamed polyurethanes is, however, that much dust tends to rise in cutting work, contaminating the working environment. That is especially the case with polyurethane moldings in which inorganic fillers such as talc and calcium carbonate are used in large quantities to improve the dimensional stability and those of which the density is lowered for better manual workability. And demands have been voiced for an improvement in that aspect.
It is an object of the present invention to provide a rigid foamed polyurethane which is largely free from dust-scattering in cutting work.
It is another object of the present invention to provide a composition from which such a low dust-scattering foamed polyurethane can be obtained.
It is still another object of the present invention to provide a model made of such a low dust-scattering foamed polyurethane.